【摘要】：隨著我國城市化進(jìn)程的不斷深入推進(jìn),城市地下空間得到空前開發(fā),基坑工程大量涌現(xiàn)�；邮┕�(huì)打破場(chǎng)地初始應(yīng)力平衡狀態(tài),引發(fā)圍護(hù)結(jié)構(gòu)變形、地表沉降和周邊土體發(fā)生位移,對(duì)周邊環(huán)境造成不利影響�；又ёo(hù)作為臨時(shí)性支撐結(jié)構(gòu),其設(shè)計(jì)使用年限一般較短。但工程建設(shè)可能會(huì)因資金短缺和設(shè)計(jì)變更等而出現(xiàn)長時(shí)間停工,形成閑置基坑。由于土體蠕變、濕化作用、降水固結(jié)和混凝土徐變等因素,使得基坑隨著閑置時(shí)間的增長而變形加大,即基坑變形具有時(shí)間效應(yīng)。時(shí)間效應(yīng)會(huì)加劇基坑工程對(duì)周邊環(huán)境安全的潛在威脅。本文以昆明某環(huán)境復(fù)雜閑置內(nèi)支撐深大基坑為研究對(duì)象,通過三維數(shù)值模擬分析基坑的長期變形,根據(jù)模型分析和現(xiàn)場(chǎng)調(diào)查結(jié)果,進(jìn)而提出基坑變形控制措施,最后采用數(shù)值方法分析加固效果。主要研究內(nèi)容如下:(1)建立基坑、地下連續(xù)墻和地鐵結(jié)構(gòu)三維整體數(shù)值模型,分析基坑開挖過程中圍護(hù)結(jié)構(gòu)、區(qū)間盾構(gòu)遂道、地鐵車站,存車線結(jié)構(gòu)的受力變形情況,通過比較模型計(jì)算結(jié)果和現(xiàn)場(chǎng)監(jiān)測(cè)數(shù)據(jù),驗(yàn)證所建模型的可靠性。(2)從土體蠕變、濕化作用、降水固結(jié),混凝土徐變等方面,分析基坑長期變形的影響因素和作用機(jī)理,進(jìn)而建立模型分析所需土體及鋼筋混凝土支撐強(qiáng)度參數(shù)的簡化方法。(3)通過試驗(yàn)方法獲得基坑閑置后土體及支撐結(jié)構(gòu)的強(qiáng)度參數(shù),采用有限元方法建立考慮時(shí)間效應(yīng)的整體時(shí)變模型,對(duì)基坑閑置前后整個(gè)開挖過程進(jìn)行三維數(shù)值模擬,將計(jì)算結(jié)果與不考慮時(shí)間效應(yīng)的非時(shí)變模型分析結(jié)果進(jìn)行比較,分析基坑長期變形特性及對(duì)周邊地鐵結(jié)構(gòu)受力變形的影響。(4)基于時(shí)變模型計(jì)算結(jié)果,結(jié)合閑置期間對(duì)基坑自身及周邊環(huán)境潛在安全風(fēng)險(xiǎn)的分析,提出基坑長期變形控制措施,并分析了加固措施的可靠性。
[Abstract]:With the development of urbanization in China, urban underground space has been developed unprecedentedly, and foundation pit engineering has emerged in large numbers. The foundation pit construction will break the initial stress equilibrium state of the site, cause the deformation of the enclosure structure, the surface settlement and the displacement of the surrounding soil, which will have a negative impact on the surrounding environment. As a temporary supporting structure, the design life of foundation pit support is generally short. But the construction may be stopped for a long time due to the shortage of funds and design changes, forming idle foundation pit. As a result of soil creep, humidification, dewatering and consolidation, concrete creep and other factors, the foundation pit deformation increases with the increase of idle time, that is, the foundation pit deformation has a time effect. The time effect will aggravate the potential threat to the surrounding environment safety caused by foundation pit engineering. In this paper, a deep and large foundation pit with complex idle inner braces in Kunming is taken as the research object. The long-term deformation of the foundation pit is analyzed by three-dimensional numerical simulation. According to the results of model analysis and field investigation, the deformation control measures of foundation pit are put forward. Finally, numerical method is used to analyze the reinforcement effect. The main research contents are as follows: (1) the three-dimensional numerical model of foundation pit, underground continuous wall and subway structure is established. The reliability of the model is verified by comparing the results of model calculation and field monitoring data. (2) from the aspects of soil creep, humidification, dewatering and consolidation, concrete creep, the influencing factors and mechanism of long-term deformation of foundation pit are analyzed. Then a simplified method for analyzing the required soil mass and reinforced concrete bracing strength parameters is established. (3) the strength parameters of the soil and bracing structure after foundation pit is idle are obtained by the test method. A global time-varying model considering time effect is established by using finite element method. The whole excavation process before and after foundation pit idling is simulated by three-dimensional numerical simulation. The results are compared with the results of time-invariant model without time effect. The long-term deformation characteristics of foundation pit and its influence on the deformation of surrounding subway structure are analyzed. (4) based on the results of time-varying model, the potential safety risk of foundation pit itself and surrounding environment during idle period is analyzed. The long-term deformation control measures of foundation pit are put forward and the reliability of reinforcement measures is analyzed.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU753

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